1. Technical Field
The present disclosure relates to an information processing method, an information processor, and a recording medium.
2. Description of the Related Art
A file format used in a conventional optical disk such as a DVD and a Blu-ray (registered trademark) disk is an MPEG2-TS (MPEG-2 Transport Stream) scheme defined by ISO/IEC 138181-1. A file (data), which is configured by multiplexing a video stream, an audio stream, and a subtitle stream using an MPEG2-TS scheme, is recorded in the conventional optical disk.
Specifically, when the MPEG2-TS scheme is used, the video stream, the audio stream, and the subtitle stream are multiplexed while divided into each of a plurality of 188-byte TS packets, and the video stream, the audio stream, and the subtitle stream are recorded in the optical disk. The MPEG2-TS scheme is suitable for a medium, such as broadcasting and an optical disk, in which the sequentially-read and -processed data is transmitted or recorded. Therefore, even in a consumer device having a relatively small buffer capacity, the stream can efficiently be read, decoded, and played back by the MPEG2-TS scheme.
On the other hand, recently an MP4 scheme defined by ISO/IEC 14496-12 is becoming widespread as the file format in content distribution of a network. An extremely flexible data structure is used in the MP4 scheme on the assumption that the MP4 scheme is applied to the randomly accessible medium such as an HDD (Hard Disk Drive) and a flash memory. In a general use form of the MP4 scheme, the stream such as the video stream, the audio stream, and the subtitle stream is divided into units of fragments having a several seconds, and the fragments are sequentially arrayed to form one file.
A high-quality content such as 4K is expected to become widespread from now on. It is considered that the optical disk is frequently used as the medium distributing the high-quality content from the viewpoint of a bit unit price. On the other hand, although a mobile device such as a smartphone and a tablet does not include a drive (optical disk drive) that can play back the optical disk, the mobile device is used as a content distribution receiving and playing back terminal in the network because of high portability and a large, high-definition display screen.
However, mobile devices such as a smartphone and a tablet are mainly compatible with the MP4 scheme, while few mobile devices are compatible with the MPEG2-TS scheme.
Therefore, in order to use the optical disk content in mobile devices such as a smartphone and a tablet, it is necessary to convert the file format of the content into the format that can be used by the mobile device. For example, PTL 1 discloses a technology of converting the file format of the content distributed by the optical disk from the MPEG2-TS scheme to the MP4 scheme. An MP4 scheme file (MP4 video content) is generated by a method disclosed in PTL 1.